Compound air-compressor.



No. 880,125. PATENTED FEB,'25, 1908.

N. A. CHRISTENSEN. COMPOUND AIR COMPRESSOR.

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APPLIGATION FILED NOV. 11. 1902.

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N. A. CHRISTENSEN.

COMPOUND AIR COMPRESSOR.

APPLIOATION TILED NQV.11. 1902.

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PATENTED FEB. 25, 1908.

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UNITED STATES PATENT omen.

NIEIIS ANTON CHRISTENSEN, OF MILWAUKEE, WISCONSIN.

GOMP OUND AIR-COMPRESSOR.

Application filed November 11. 1902. Serial No. 130.895-

To all whom it may concern:

Be it known that I, N IELS ANTON CHRIS- TENSEN, residing at Milwaukee, Milwaukee county, WVisconsin, have invented certain new and useful Improvements in Compound AirCompressors, of which the following is a specification.

My invention relates to compound air compressors and the object thereof is to provide an efficient and reliable machine of this character. In the present instance, a two stage compressor is shown with the cylinders arranged in axial alinement and having a common piston' My invention also contemplates a novel and efficient arrangement of inter-cooler and of single head for the discharge and suction valves of the adjacent ends of high and low pressure cylinders.

The novel and advantageous features in the construction and operation of my compressor will be readily understood from the description hereinafter given.

In the drawings, Figure 1, is a central longitudinal section of my compressor and the actuating crank shaft and connections, and illustrating, in elevation, a portion of the electric motor by which I prefer to operate the crank shaft; Fig. 2 an elevation of the left hand face (Fig. 1) of the middle head between the two compressing cylinders; Fig. 3 a side elevation of this head with a portion thereof broken away and showing in section Fig. 4 an elevation of the right hand face ofsuch head and Fig. 5 a detail view of one of my seamless, imperforate high pressure cylinder valves, illustrative of the structure of all the valves, both suction and discharge.

-By preference my compressors and their actuating mechanism are mounted on a common sub-base 1, whereby the entire machine is made compact and self-contained, and moreover the proper position and alinement of the various parts are properly maintained.

Starting with the description of the driving mechanism, my compressors are operated by means of a crank shaft 2, having a suitable connecting rod 3, reciprocating a cross head 4 which is connected to a piston rod 5. Suitable motive power for driving the crank shaft may be adopted but I prefer to use an electric motor 6, geared or otherwise operatively connected to the crank shaft.

The crank shaft works in a casing 7, supported on and connected to the sub-base Specification of Letters Patent.

Patented Feb. 25, 1908.

and completely inclosing the parts within, thereby efiectually protecting them from dust, dirt, etc. Although the automatic lubrication of the machine constitutes no part of my present invention, yet, inasmuch as it is illustrated in the drawings, I will state that the bottom of the inclosing casing is in the form of an oil-well in which the crank dips, thereby splashing or throwing oil into an oil pan or receptacle 8 from which the oil is delivered to the main crank-shaft bearings and also into the trough 9 formed in or arranged on the connecting rod. From the trough, the oil flows or is forced through a hole 10 to the crank, and through a hole 11 in the other end of the'connecting rod. to the wrist pin. Thence the oil may flow through the central passage 12 in the piston rod 5 andthrough the radial passages 13 and 14 of the pistons hereinafter described. The cross as double acting, comprises a cylinder 16 in which travels a piston 17 secured to the piston rod 5. The back valve head 18 is secured to one end of the cylinder 16 and contains suction and discharge valves of suitable construction and arrangement for governing the inlet and outlet of air to and from the cylinder on the left hand side of the compressing piston 17, Fig. 1. By preference, however, I employ my imperforate, seamless cylinder type of valve such as shown in myprior patent issued to me on August 20, 1901, No. 680,842. As hereinbefore stated, the guide frame 15 is secured to the low pressure compressor, or rather to the valve head 18, and in the present instance the same bolts 19 are used for fastening both the frame and the head to'the cylinder. This head is provided with a suitable stuffing box 20 for the piston rod, as clearly illustrated in Fig. 1.

The high pressure cylinder 21, in which travels a compressing piston 22 secured to the piston rod 5, is arranged beyond the low pressure cylinder, in tandem or axial alinement therewith. Intermediate the two cyl inders is arranged a middle head 23 which is a combined cylinder head and valve head, and in this instance containing two sets of suction and discharge valves, one set for governing the inlet and outlet of the right hand end of the low pressure cylinder and the other set for governing the inlet and outlet of the left hand end of the high pressure cylinder, Fig. 1. As shown, the high pressure cylinder has flanges 24, through which and the middle head pass bolts 25which engage the other cylinder whereby said parts are held together. The high pressure cylinder is closed at its outer or front end by means of a head 26 containing suitable suction and discharge valves for governing the inlet and outlet to and from the right hand end (Fig. 1) of such cylinder.

Referring to my novel construction and arrangement of middle head, the details thereof will be readily comprehended from Figs. 2, 3 and 4. The low pressure side of the head is shown in Fig. 2, and the same is provided with a suction port 27 and a discharge port 28. The suction enters the elbow connection 29 and head through a passage 30 which communicates with the lower end of a cylindrical chamber 31 in which is arranged the suction valve, normally seated to govern. the communication with the suction port 27. This suction valve is the same, except in proportions, as the valve illustrated in Fig. 5. through the port 28 lifting a discharge valve arranged in the cylindrical chamber 32 and passing through the discharge passage 33 and through the elbow connection 34.

The suctionand discharge ports and passages in the middle head for the high pressure cylinder are shown in Figs. 3 and 4, Fig. 4 representing the high pressure cylinder side of such middle head. The suction is through the side opening or passage 35, thence upwardly, raising the suction valve 36 arranged in the cylindrical chamber 37, and finally entering the high pressure cylinder through the suction port 38. The discharge is through the discharge port 39, lifting the discharge valve arranged in the cylindrical chamber 40, and thence laterally through the passage 41. Illustration of all of the various valves is omitted inasmuch as they are of the type 7, shown in Fig. 5 and as their omission. from Figs. 2, 3 and 4 permits the various passages to be more clearly understood. The piston rod, which is common to both piston heads, passes through the head 18, as described, and also through the head 23, in the latter one of which a stuffing box 23 is arranged.

The discharge of the low pressure cylinder is arranged to be cooled before delivery to the suction of the high pressure cylinder, and, to this end, the discharge from the low pressure cylinder is collected by pipes 42 joined to or communicating with a common discharge pipe 43, as shown by dotted lines in Fig. 1. This pipe 43 communicates with a hollow head 44 secured, as a closure, to the The discharge occurs front end of a cooling chamber 45 formed in the lower portions of the sub-base 1 and through which cold water circulates. This head 44 has an upper passage or manifold 44 and a lower passage or manifold 44" which are connected together by one or more, preferably a plurality, of cooling coils or tubes 46, submerged in the cooling chamber. The manifold 44' communicates with the discharge pipe 43 and the manifold 44" with a pipe 47 connected to the head 44 and designated the high pressure suction pipe in asmueh as it forms the suction for the high pressure cylinder. This pipe 47 communicates with pipes 48 extending longitudinally of the high pressure cylinder, which pipes 48 communicate in turn with the suction passage of the middle head and with a similar passage in the other head 26, all as indicated by dotted lines in Fig. 1. The delivery from this high pressure cylinder from the passage 41 and from a similar passage in the head 2h may be collected in suitable manner so as to discharge in a single pipe which leads to a storage reservoir or place of use.

The cylinders, as shown, are water jacketed and likewise the heads are hollow and connected to the water circulation. with the result that the various passages, valves and parts generally are effectually cooled. The intercooler here consists of tubes submerged in cold, circulating water and of such pro portions that by the time the air has circulated through them it has been cooled down to approximately the same temperature as the circulating water before it is drawn in through the suction valves of the high pressure cylinder. It is obvious of course that the arrangement may be reversed in this that the compressed air may be on the outside and the water inside the tubes. Furthermore, while I have herein shown and described a two stage compressor, yet to obtain further compression, one or more additional cylinders could be added in tandem or axial alinement with the two cylinders described but instead of thus adding cylinders, I prefer to duplicate the machine and put proper gearing between the machines so that they shall run in unison, with the result that the air is compressed. in the low pressure cylinder of the first machine, then in the second. stage cylinder thereof, after being cooled. in the intercooler, then transferred to another intercooler, delivered to said compressor in the first cylinderof the other compressing set or machine, thence delivered to another intercooler and to the secondv cylinder of such sec ond machine, and finally to the after-cooler or reservoir as may be desired.

By the construction shown, I provide a simple, andreliable arrangement of parts for the efficient andv proper compression of air. Furthermore, the middle head, which is a combined cylinder head and valve head for the piston heads on a common piston rod and the extending thereof through a common head results in a simple but powerful and well balanced compressor.

I claim:

dependent of their pistons and imperforate and valveless pistons in said cylinders.

2. A compound compressor formed as a unitary structure with low and high pressure cylinders, arranged in tandem, said cylinders being double acting and having between them a head common to both and containing the suction and discharge valves of the adj acent ends of the low and high pressure cylin- 10 1. A compound compressor power as a uniders respectively and imperforate and valvetary structure with low and high pressure less pistons in said cylinders. cylinders arranged in tandem and having be- NIELS ANTON CHRISTENSEN.

tween them a valve head common to both of Witnesses: them, connections for compressed air be- R. L. GRUBER, 15 tween said cylinders but extraneous and in- J NO. DADMUN. 

